1. Field of the Invention
The present invention relates to a vehicle and an engine controlling method, in which a plurality of engine control components are controlled in accordance with an acceleration command input by a driver to change an engine driving power.
2. Description of the Related Art
Generally, a reference value of an amount of a fuel fed to an engine is predetermined so as to correspond to an engine speed and a throttle valve opening degree. A controller for controlling an operation of the engine is configured to decide the fuel feed amount predetermined as the reference value based on the engine speed, the throttle valve opening degree, and other values received from sensors, and cause an injector to inject a fuel to an intake-air in an air-intake passage with the decided fuel feed amount. In an engine mounted in a recent vehicle, a fuel stop control for stopping fuel injection to the engine is executed when a throttle valve is closed and a vehicle is decelerated, for the purpose of improving a fuel efficiency, and other purposes, and fuel injection is resumed when the throttle valve is opened (see Japanese Laid-Open Patent Application Publication No. 2005-76600).
During the fuel stop control, a fuel adhering to an air-intake pipe before the fuel stop is suctioned into the engine and the air-intake pipe is dried. In a normal state, an air-fuel ratio is set such that a fuel in an air-fuel mixture is rich. When the throttle valve is opened and the fuel injection is resumed to accelerate the vehicle in a fuel stop control state, the injected fuel adheres to the dried air-intake pipe, so that the fuel in the air-fuel mixture suctioned into the engine becomes lean for a moment and becomes rich thereafter. Under this condition, the engine driving power fluctuates when the fuel injection is resumed and the vehicle is accelerated, which degrades drivability. For example, during cornering, a driver feels nervous about a vehicle body vibration, etc. Therefore, there is a need to suppress a fluctuation in the engine driving power which would occur when the fuel injection is resumed in the fuel stop state.
In a state where a throttle valve opening degree is small, combustion energy is smaller than a mechanical resistance of the engine. A crankshaft rotates by an inertia force transmitted from a drive wheel When the throttle valve is closed to decelerate the vehicle in a high engine speed condition during driving, combustion does not occur in the engine due to a deficiency of an air-intake amount. When the throttle valve is opened to accelerate the vehicle under this state, an engine suddenly transitions from a non-combustion state to a combustion state. This makes drivability worse.